A. Survival of the fittest and natural selection are interchangeable terms.
Somewhat met in the nature
Explanation:
A pulsar is a rapidly rotating neutron star which emits large amounts of electromagnetic radiation and particle jets. A neutron star is what is left over when a star 4 - 8 times the mass of our sun burns up most of its fuel and explodes in a supernova.
They are found in the gonads, or testes and ovaries